An extensive evaluation flow cytometric evaluation continues of patients with autoimmune lymphoproliferative syndrome (ALPS) and their extended-family members. The evaluation is based on characterization of the expanded double negative T-cell and B-cell populations. To date, the double negative T-cells have been demonstrated to be alpha beta TcR, CD57+, HLA-DR+, and CD45RA+. The phenotypic findings in the peripheral blood have been correlated with the histologic and phenotypic findings in the lymph tissue.